Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 11: Spindependent Transportphenomena II
MA 11.9: Vortrag
Montag, 25. Februar 2008, 17:15–17:30, H 0112
Electrical Nonlinearity in Manganite Films — •Vasily Moshnyaga1, Kai Gehrke1, Lakshmana Sudheendra1, Stephanie Raabe1, Konrad Samwer1, Alexandr Belenciuc2, Oleg Shapoval2, Oleg I. Lebedev3, and Gustaaf van Tendeloo3 — 1I. Physikalischers Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — 2Institute of Applied Phyiscs, Academiei 5, MD-2028, Chisinau, Moldova — 3EMAT, University of Antwerp, Groeneborgerlaan 171, B-2020 Antwerpen, Belgium
We address the nature of nonlinear electrical 3rd harmonic voltage in epitaxial La0.7Ca0.3MnO3 (LCMO) and La0.7Sr0.3MnO3(LSMO) manganite films. In LCMO the nonlinearity is strongly enhanced only close to the para-ferromagnetic phase transition (Tc=270 K) and can be suppressed by magnetic field, showing very large nonlinear CMR~10(5) %. In the low temperature ferromagnetic metallic state the nonlinearity is small, -90 dB, and comparable to that for a metallic resistor. In contrast, LSMO is an essentially linear metallic material in the whole range of temperatures, T=4-400 K, and magnetic fields, B=0-5T. Such an intrinsic nonlinear behaviour is consistent with the temperature dependence of correlated polarons in LCMO and the absence of correlated polarons in LSMO.